It's hard to say for sure without reading it, but likely there will be three main characters who are the new sannin. They could be students of the original sannin or completely new characters with no direct connection but similar in their skills and importance.
One idea could be that they go on a mission together to a far - off land. Naruto uses his new - found Rasengan variations, Sasuke with his evolved Sharingan techniques, and Sakura with her enhanced medical and combat skills. They face a powerful enemy that was once defeated by the original Sannin and they have to use their combined skills to overcome it.
Perhaps they are three young wizards from a far - off land. They could be from a place where magic is practiced differently, like a tribe deep in the Amazon where they use magic to communicate with animals. So when they come to Hogwarts, they have a lot to learn and also a lot to teach. They might have unique magical abilities that are rare in the Hogwarts world, such as the ability to control the weather without a wand.
Well, it could be some of the younger generation characters who have shown great potential. For example, Boruto could be one of them, as he has his own unique set of skills and abilities. Another could be Sarada, with her Sharingan and growing ninja skills. And maybe Mitsuki, with his snake - like abilities.
Well, one interesting concept could be the new abilities the characters might have. Maybe they develop unique jutsu that combine different elements in unexpected ways. Another could be the relationships between the new sannin, whether they have rivalries or strong bonds of friendship like the original sannin.
It could be Jiraiya. He has a really strong bond with Naruto already. He's taught Naruto a lot in the original story too. So in the fanfic, his training could be the most in - depth, covering things like advanced rasengan variations and how to fight against really powerful enemies. His influence on Naruto's character development would also be significant.
One idea could be the new Sannin facing a powerful new enemy that threatens the entire ninja world. They have to combine their unique skills, like one being a master of genjutsu, another of taijutsu, and the last of ninjutsu, to overcome it.
Well, they could start by having a friendly competition among themselves to see who has improved the most. This could lead to them realizing their combined potential. Then, they get called upon to deal with a threat that the old Sannin once faced but in a new and more dangerous form. Naruto might use his positive energy to boost the morale of the people around them, Sasuke would analyze the enemy's weaknesses, and Sakura would be ready to heal any injuries.
Well, if Naruto becomes a Sannin, he would surely gain some amazing new abilities. For one, he could inherit Tsunade's healing abilities. This would be a great addition to his skills as he could not only fight but also heal his comrades on the battlefield. In terms of Jiraiya, Naruto might be able to master more advanced forms of Rasengan, inspired by Jiraiya's own jutsu creativity. And from Orochimaru, he could get a better understanding of the chakra nature and how to manipulate it in more complex ways, like Orochimaru did with his snake - like jutsus.
Jiraiya would be the most interesting. He has a wild and carefree personality which could be a great contrast to Naruto's initially lonely and neglected state. Jiraiya is also very knowledgeable about the outside world and has many powerful jutsus, especially those related to the toads. He could take Naruto on adventures, teaching him not just about being a ninja but also about life in general. His connection to the prophecy about the 'Child of Prophecy' could also add an interesting layer to the story, as Naruto might be groomed in a different way to fulfill that prophecy under Jiraiya's guidance.